PCI/DPC: Use threaded IRQ for bottom half handling

Remove the work struct that was being used to handle a DPC event and use a
threaded IRQ instead.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Sinan Kaya <okaya@kernel.org>
Reviewed-by: Oza Pawandeep <poza@codeaurora.org>

drivers/pci/pcie/dpc.c

@@ -17,7 +17,6 @@
 
 struct dpc_dev {
 	struct pcie_device	*dev;
-	struct work_struct	work;
 	u16			cap_pos;
 	bool			rp_extensions;
 	u8			rp_log_size;
@@ -160,10 +159,10 @@ static void dpc_process_rp_pio_error(struct dpc_dev *dpc)
 	pci_write_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_STATUS, status);
 }
 
-static void dpc_work(struct work_struct *work)
+static irqreturn_t dpc_handler(int irq, void *context)
 {
 	struct aer_err_info info;
-	struct dpc_dev *dpc = container_of(work, struct dpc_dev, work);
+	struct dpc_dev *dpc = context;
 	struct pci_dev *pdev = dpc->dev->port;
 	struct device *dev = &dpc->dev->device;
 	u16 cap = dpc->cap_pos, status, source, reason, ext_reason;
@@ -194,6 +193,8 @@ static void dpc_work(struct work_struct *work)
 
 	/* We configure DPC so it only triggers on ERR_FATAL */
 	pcie_do_fatal_recovery(pdev, PCIE_PORT_SERVICE_DPC);
+
+	return IRQ_HANDLED;
 }
 
 static irqreturn_t dpc_irq(int irq, void *context)
@@ -210,7 +211,7 @@ static irqreturn_t dpc_irq(int irq, void *context)
 	pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
 			      PCI_EXP_DPC_STATUS_INTERRUPT);
 	if (status & PCI_EXP_DPC_STATUS_TRIGGER)
-		schedule_work(&dpc->work);
+		return IRQ_WAKE_THREAD;
 	return IRQ_HANDLED;
 }
 
@@ -232,10 +233,10 @@ static int dpc_probe(struct pcie_device *dev)
 
 	dpc->cap_pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC);
 	dpc->dev = dev;
-	INIT_WORK(&dpc->work, dpc_work);
 	set_service_data(dev, dpc);
 
-	status = devm_request_irq(device, dev->irq, dpc_irq, IRQF_SHARED,
+	status = devm_request_threaded_irq(device, dev->irq, dpc_irq,
+					   dpc_handler, IRQF_SHARED,
 					   "pcie-dpc", dpc);
 	if (status) {
 		dev_warn(device, "request IRQ%d failed: %d\n", dev->irq,